What are calories?

What are calories?

Defining the definition of calorie isn't hard: according to most textbooks on science, is the energy needed to increase the weight of one gram of water just one degree Celsius. How does this apply to the caloriecounts that are displayed everywhere from menus for fast food to the nutrition labels of snack bars

When we consider caloriecounts are usually trying to determine the amount of energy we're pumping to our bodies. But a nutrition label will not give you this, at the very least, completely. There are too many variables to consider, many of that are influenced by the individual's physical condition, and some of them are still working out.

Consider this: Starting in 2020 almonds suddenly appeared to have about 30% less calories than they had in the year before. Nuts and cashews both experienced a similar drop on energy density. The nuts themselves did not change, naturally, but the method employed to calculate calories did.

That's because there's a reason that the FDA and USDA often still use a century-old method for measuring calories. This method was created in the 19th century (though exceptions are made if there's more current research available, for instance, for those who are nuts). In the 18th century Wilbur Atwater, decided to gauge the amount of energy in food items by burning the substance, quantifying how much energy was contained in it as well as feeding the same food items to people and measuring how much energy is contained in their poop and pee. The difference in energy in and energy out, or so, became the calorie-calculating numbers that we have today for macronutrients 9 calories in a gram fat, and 4 calories in grams of carbohydrate, and protein.

In the 19th century this was an enormous leap in the understanding of energy density of food. But for the 21st, the results don't match up.

[Related The truth about the counting of calories[Related: The truth about counting calories

For instance, a calorie of fat from a nut for instance, does not appear to be the same thing as an calorie in animal fat. While it's unclear what causes this and why, it's likely that our bodies aren't able to break down all foods equally, which means certain calories remain within the food and are released into our poop, never having an impact on our waistlines. (We should be aware that the research into the calories found in nuts was partly funded by various nut boards, though they didn't conceptualize or conduct the research).

Bioavailability is only recently been made a focus of investigation, and therefore there's not a lot of information on what other types of food items we're ill-informed about measuring. We know, for instance that cooking food appears to make the nutrients that are in it more easily accessible. We are also aware that our unique microbes within our gut help determine how much energy we extract from our food, like by degrading the cell walls of certain vegetables. The Atwater system doesn't take into account all for cooking food, much less the way you cook it, neither does it take into account differences in bioavailability between different kinds of foods. It simply focuses on the number of grams of protein, fat or carbohydrate is present in the food.

The new nut studies don't even use a much more advanced method than Atwater utilized. The basic idea is that the researchers fed almonds (or cashews or walnuts) to participants, and the study measured their poop in order to determine how much energy was absorption. It's not that the USDA scientists took the time to study one food item in particular.

As long as we don't find a better way to measure the energy contained in each food group that is the term calorie is, in reality is just a number we've allocated arbitrarily to food items. Don't consider it a serious matter.